1. Field of the Invention
The invention relates to devices for perforating sub-chondral bone within a joint of a patient.
2. Description of the Related Art
Cartilage on the articular surfaces of bones at joints within a body provide important protection for the underlying bone. The portions of bone supporting the articular cartilage are often referred to as sub-chondral bone. Both acute and chronic injury of articular cartilage causes chondral defects which can lead to progressive joint pain and impaired mobility.
Microfracture is an increasingly desired reparative procedure involving selective perforation of sub-chondral bone. There are a number of studies showing that microfracture beneath a chondral defect can result in a blood clot filling the chondral defect with pluripotent marrow-derived mesenchymal stem cells that produce beneficial fibrocartilage repair tissue.
Surgeons typically first debride unstable cartilage down to the sub-chondral bone layer to support subsequent basilar integration of the new repair tissue. Microfracture usually is accomplished thereafter using one or more rigid, curved awls that are manually manipulated through arthroscopic access sheaths or cannulas, and sometimes struck with a mallet, to create a series of microfracture holes in sub-chondral bone. Working space around chondral defects is usually limited and it is difficult to manipulate the awls effectively, especially within hip joints. A surgeon may need to exchange awls of different curvatures at different stages of the procedure. The cutting tips of the awls are exposed during insertion and withdrawal as well as during actual use on bone. Skiving of the awl tip across bone, often causing longitudinal disruptions and potential weakening of sub-chondral bone, and other unintended injury to bone and other tissue can occur.
It is therefore desirable to have a device insertable within a joint of a patient that easily enables multiple perforations of sub-chondral bone, even within a small working space.